Lethargic Puffer

Question
QUESTION: Hello, my green spotted puffer fish is about 1.5 inches in length living in a 10 gallon brackish aquarium. He is usually active and swimming about and being caught in the bubbles of his arrator and filter. lately he is becoming increasingly lethargic and just sits on the bottom of the aquarium for as long as an hour at a time. His fins don't move as often as they have been and his gills are often still. I was wondering if this is caused by some sort of illness in the water or if it is from a new piece of dead coral i found along a beach and added recently. If you could help me and tell me what I can do to help my little puffer I would much appreciate it. Thanks!

Will

ANSWER: Hello Will,
What are you feeding your puffer? They need to have a diet consisting mainly of snails, brine shrimp, bloodworms, ghost shrimp, mussels, clams, etc.
They will not eat flakes, and even if they do they will get no nutritional value from them as they are carnivores only.
You should never add random things found outside to your tank. If you want more decor, only buy decor made specifically to go into your tank from pet stores.
The dead coral may have had some sort of parasite, or some sort of chemical on it, or possibly is leeching something into the water.
Remove it straight away and doing some small frequent water changes.
You should be doing a lot of water changes anyway, as puffers tend to be very messy fish and can make the water full of ammonia very quickly.
If this is a newly set up tank that is even worse, because you will have no biological filter to help you out.
Make sure you have a decent filter on your ten gallon, such as a bio-wheel, and keep his temperature at about 79 degrees.
They are tropical fish and must have heaters in their tanks.
Last but not least, Green Puffers grow to a length of about six inches, and you should start saving up for a larger tank for him. 28 gallons is my recommendation as a MINIMUM. Six inches doesn't sound very big, but it is.
Hopefully all this helped, and remember from now on to do plenty of research on any pet before you get it!

---------- FOLLOW-UP ----------

QUESTION: Hello again, like you said I should be I am feeding my puffer shrimp, snails, and bloodworms. I have removed the corral and done water changes of almost the whole tank. He is still being quite lethargic after two days though. He has a 30 gallon rated filter with an active biozyme community. Do you think there still could be something still in the water from the corral? Can puffers be lethargic from too high salinity? (I accidentally added a little too much salt and his tank is fully saltwater now... I'll be changing that though) And yes I will be getting a larger tank. It will be 100 or more gallons so he'll have plenty of swimming room. My puffer has survived many diseases and infections over the months I've had him, so I think this is something new. Could there still be something in the water from the corral? And do higher salinities make puffers and other fish lethargic? If so I think that might be why he is acting funny. Thanks for your help so far and I think this will help a lot!

Will

Answer
Yes there could still be something in the water. Just keep doing small frequent water changes and it should help. Most puffers start out freshwater when babies, then gradually switch over to either marine or brackish, depending on the puffer. So you'll want to make sure your specific puffer is fully marine, and that you switch him over very slowly. Adding a lot of marine salt may or may not have an adverse affect on him, but it's possible he is suffocating or his system is shocked. Puffers have to gradually learn how to intake that salt in with the rest of their water. Just remember - with  EVERY animal - every change in living should be transitioned slowly so they can cope and adjust accordingly.